1. Field of the Invention
The present invention is generally directed to a sliding mechanism and a variable valve timing mechanism employing such a sliding mechanism.
2. Background Art
Japanese Patent Laid open Print No. Hei 11 (1999) 159311 discloses a variable valve timing mechanism or variable valve timing control apparatus. This variable valve timing mechanism is provided in an internal combustion engine in order to change the valve timing of intake valves or exhaust valves, to thereby change the operation timing of the intake valves or the exhaust valves in accordance with engine conditions.
In a variable valve timing mechanism of such a type, there are provided a plurality of sliding mechanisms, each of which is made up of a pair of sliding members. In the above-mentioned publication, one of the sliding members is a vane while the other is a housing. The vane and the housing are made of aluminum and Fe-family sintered material, respectively. Due to the fact that a lubrication oil provided between the vane and the housing is reserved or stored in exposed parts of the Fe-family sintered material housing, the sliding movement between the vane and the housing is made smooth and in good order. However, employing Fe-family sintered material for forming the housing makes the variable valve timing mechanism heavier, which is undesirable in a vehicle.
Thus, a need exists to provide a device which is free from the aforementioned drawbacks.